Outphasing, or linear amplification with nonlinear components (LINC), allows input signals to be amplified by highly efficient nonlinear power amplifiers operating in nonlinear regions, including at or near saturation. Each variable-envelope input signal is separated into two constant-envelope component signals. These constant-envelope signals can be processed using a chain of analog components including mixers or amplifiers that have nonlinear input-output characteristics. The two constant-envelope signals are then combined using an analog combiner to create an amplified replica of the original signal. However, due to physical differences in the analog components as well as the frequency response of the analog combiner, the amplified output signal is not a perfect amplified reconstruction of the input signal. Indeed, these imperfections in analog components may combine to introduce multiple spectral impurities into the output signal, and distort the signal in other ways.
Conventionally, backoff or nonlinear analog or digital pre-equalization (DPD) is applied to decrease nonlinear signal distortion of the signals going through the analog signal chain. Analog pre-equalization has very limited performance, while DPD is complex and inefficient. Perfect linearizations are virtually impossible. DPD's complexity is manifested in complex algorithms, requiring constant updates and additional hardware in the form of feedback loops. Additionally, due to complex algorithms, a significant amount of power is consumed in digital signal processor (DSP), field programmable gate array (FPGA), application-specific integrated circuit (ASIC), or other integrated circuits, lowering overall system efficiency. These efficiency losses are purely and directly converted to heat which is nearly impossible to recycle.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.